I purchased a 1986 nissan pickup today and noticed it will need some attention. I could use a little help with figureing it out.

1.) The truck has a weird idle problem when at idle it will jump between 900 and 2000 a constant lope.
2.) The heater core is leaking and causing the truck to overheat! I think this will be a big job but any tips would be great.

Well I think you would want to fix the heater first, you could by pass the heater with a piece of heater hose. then work on the idle make sure all the vacuum hoses at connected and not leaking, good luck

heater cores are easy to do, just time consuming. while doing check out the condition of the hoses, old age does wonders. then look into the idle problem, 1st thing would be a tuneup, check everything, plugs, wires, cap, rotor, filters and timing. then go from there.